Telephone system



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REX/N NkQu INVENTORS:O.RIMILLERH A TTORNEY Reissued Feb. 22, 1944 TELEPHONE SYSTEM Ralph E. King, Short Hills, and Ohmer R. Miller, Morristown, N. J., assignors to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Original No. 2,209,777, dated July 30, 1940, Serial No. 243,348, December 1, 1938. Application for reissue July 17, 1942, Serial No. 451,363

26 Claims.

This system relates to telephone systems and particularly to systems comprising toll offices and automatic switching means for completing toll calls.

It is the object of the invention to minimize the number of manual switching operations involved in establishing toll connections, to expedite the completion of such connections, and to more efliciently and reliabl effect the transmission of directive and supervisory signals to and through the automatic switching means employed in completing desired connections.

One of the features of thi invention is a telephone system comprising toll offices in which automatic switches are provided for routing incoming calls to called toll and local offices, the talking conductors of one or more of the trunk and selector circuits constituting a simplex circuit for controlling the operation of a relay bridged across one end of these talking conductors, supervisor signals being transmitted from a connected outgoing line or trunk to the incoming line over a non-talking conductor other than the usual sleeve or test conductor. The relay is operated due to an unbalance between the two sides of the simplex circuit when the outgoing line or trunk to which the connection is extended is of such a character as to require that the transmission pads associated with the incoming line be included in the talking circuit. If two lines, each provided with transmission pads, are connected together, the simplex circuit comprising the talking conductors of the connection is used to control the transmission pads of both lines, one relay being bridged across the talking conductors at one end of the simplex and another relay being bridged across the talking conductors at the other end of the simplex.

Another feature of the invention is the provision of a non-talking conductor between an incoming line and a connected outgoing line for transmitting supervisory signals from the outgoing line or trunk to the incoming line in combination with the provision of a simplex circuit over the talking conductors of the connection for transmitting supervisory signals from the incoming line to the outgoing line or trunk, and for controllin the short-circuiting of the transmission pads associated with the incoming line.

Another feature of the invention is a circuit arrangement whereby a calling toll operator, during the completion of a connection from an incoming line to a desired toll operator or local subscriber under the control of the calling oper ators dial, will receive a stop-dialing signal whenever the connection is extended to a trunk which is not at the time of seizure ready to receive dial impulses, and will receive a startdialing signal as soon as dialing may be resumed. According to this feature a toll route selector is arranged to transmit a stop-dialing signal to a, calling operator as soon as the brushes are selectively advanced to a group in which each of the trunks is connected to an impulse receiver in response to seizure of the trunk, the stop-dialing signal being continued by the seized trunk circuit until an impulse receiver is associated therewith. In a case where the impulses are being transmitted by a register sender, the stop dial signal can be used to stop the sending of impulses until the stop-dialing signal ends.

According to a further feature, the dial pilot lamp in an operators dial circuit is arranged to respond to supervisor signals, including a stopdialing signal, received by the-associated outgoing trunk circuit while the dia1 circuit is connected to the trunk, the disconnection of the dial circuit bein efiected only upon restoration of the dial key,

Another feature of the invention is the provision, in a toll ofilce comprising elector switches for extending connections from incoming lines to outgoing trunks, including trunks to community dial oflices in which impulse responsive apparatus is connected to a trunk as a result of its seizure, and to lines including ring-down toll lines, of supervisory signaling means individual to each selector having access to such trunks and lines for establishing the required signaling and supervisory circuits depending upon the character of a selected line or trunk.

These and other features of the invention will be further explained by considering their application in the telephone system shown schematically in the drawings of this specification. The invention is, however, not limited in its application to the system shown in the drawings and is enerally applicable to toll systems comprising selector switches for establishing connection including interofiice trunks.

Referring to the drawings:

Fig. 1 shows a toll operator's cord Cl and operators telephone;

Fig. 2 shows a toll operator's position dial circuit PDI Figs. 3 and 4 show outgoing Jacks J I, J2, answering jacks J3, J4, and an outgoing trunk circuit OTI connected to jack J I;

Fig. 5 show intertoll selectors TSI and T83, an interswitch trunk circuit ISTI and an assoficcs, and intertoll trunks.

connecting trunk circuit OTI of Fig. 3 to one.

end of intertoll trunk Tl Fig. 6A shows a two-way trunk circuit 'I'WTI connecting trunk circuit OTI of Fig. 3 to the toll route selector T8! of Fig. 5;

Fig. '7 shows a composite signaling circuit CS2 at the other end of intertoll trunk Tl Fig. 7A shows a two-way trunk circuit 'IWT2;

Fig. 8 shows toll route selector TSZ associated with the two-way trunk circuit TWTZ of Fig. 7 and toll route selector TS4 associated with the two-way trunk circuit TWTI of Fig. 9;

. Fig. 9 shows outgoing lacks J5 and J 6 and an outgoing trunk circuit T2 connecting jack J to the composite signaling circuit CS2 of Fig. 7 and trunk circuit TWT2 of Fig. 7A; Fig. 9 also shows an outgoing trunk circuit 0T4 connecting jack J6 to the associated two-way trunk circuit TWT4 and though the composite signaling circuit CS4 to an intertoll trunk T4;

Fig. 10 shows answering jacks J1 and J8, an

incoming trunk circuit IT2 connecting Jack J1 'to a set of terminals in the bank of selector AS2 of Fig. 14;

" Fig. 11 shows an interswitch trunk circuit IST2 connected to sets of terminals in the banks of selectors T82 and T84 of Fig. 8;

Fig. 12 shows an operator's position circuit PC2 and a cord circuit C2 for connection with jacks J5, J6, J1, J8, J9, Jill, 'JH and Jl2 of Figs. 9, 10, and 16;

Fig. 13 shows a dial circuit DC2 associated with theposition circuit PC2 of Fig. 12;

Fig. 14 shows an auxiliary toll route selector AS2 connected to the trunk circuit IST2 of Fig. 11;

Fig. 15 shows a ring-down toll line circuit EDI and jacks J 9 and J I 0 associated with a ring-down toll line RDL;

Figs. 16 and 17 show a two-way trunk circuit CDTI connecting one end of a trunk CDT to terminals in the bank of selector AS2 of Fig. 14;

Fig. 18 shows a two-way trunk circuit CDTZ in a community dial ofiice at the other end of trunk CDT, a trunk finder TF and incoming selector IS, a connector C, a line finder LFI and first selector SI, and two subscribers stations A and B; and

Fig. 19 shows the relative position of each of Figs. lto. 18, inclusive, to form an intertoll dialto a community dial office, or to an intertoll trunk. Outgoing jacks connect to switching trunks, toll lines, trunks to community dial offices, and intertoll trunks. Answering jacks are directly connected to recording trunks, toll subscribers lines, trunks from community dial of- Toll route selectors and auxiliary toll route selectors are provided for use on calls incoming over intertoll trunks to establish connections with called toll, local, or community dial offices. The operators positions are provided with dials for use in controlling the operation of incoming and auxiliary toll route selectors in other toll ofiices and for controlling the operation of selector and connector switches in local or community dial offices. While not shown in the drawings, the operators positions may be provided with key-sets in place of dials, in which case senders are associated with the outgoing trunks to register the key-set impulses and control the selectors.

The toll board in one toll office is represented by an operators cord Cl and position dial circuit PDI, the outgoing jacks J I and J2 and the answering jacks J3 and J4. The jack J I, outgoing trunk OTI, two-way trunk circuit TWTI, incoming toll route selector TSI, and the composite signaling circuit CSI are all associated with a two-Way intertoll trunk Tl, the distant end of which terminates in a second toll office. The jack J2, outgoing trunk circuit 0T3, two-way trunk circuit TWT3, incoming toll route selector TS3 and composite signaling circuit CS3 are all associated with a two-way intertoll trunk T3, the distant and of which terminates in a third toll office. The incoming toll route selectors, such as TSI and T83, have access to auxiliary toll route selectors. The auxiliary route selectors, such as As l, have access to toll lines, intertoll trunk, switching trunks leading to the local oflices, trunks leading to community dial offices, and to incoming trunk circuits terminating at a toll operators positions, such for instance, as the trunk circuit ITI connecting to answering jack J3. Interswitch trunk circuits such as ISTI are associated with auxiliary route selectors having access to ring-down toll lines Dr to community dial ofiices of the link type, that is, offices in which impulse responsive apparatus is connected to a trunk in response to its seizure at the toll ofiice.

The toll board in the second toll office is represented by the operator' cord C2, position circuit PC2, dial circuit DCZ, and jacks J5 to J l2, inclusive. The lack J5, outgoing trunk circuit 0T2, two-way trunk circuit TWT2, incoming toll route selector T52, and composite signaling circuit CS2 are all associated with the intertoll trunk Tl connecting with the first toll ofiice. The jack J 5, outgoing trunk circuit 0T4, two-way trunk circuit TWT4, incoming toll route selector T54 and composite signaling circuit CS4 are all associated with an intertoll trunk T4 leading, to a fourth toll oilice. The incoming toll route selectors TSZ and T54 have access to auxiliary toll route selectors. The auxiliary selectors, such as ASZ, have access to toll lines, intertoll trunks, switching trunks leading to local ofiices, trunks to community dial offices and to incoming trunk circuits such as IT2 connecting to answering Jack J1. Interswitch trunk circuit ISTZ is individual to the auxiliary selector AS2 which has access to both ring-down lines such as RDL and trunks, such as CDT, to community dial oil-ices of the link type.

The outgoing trunk circuits OT! and GT2, incoming two-way trunk circuits TWTI and TWT2, toll route selector circuit TSZ, interswitch trunk circuit ISTZ, auxiliary toll route selector A52, incoming trunk circuit IT2, ring-down toll line circuit EDI, and community dial ofiice trunk circuits CDT! and CDT2 are all shown in detail. 

